Equal impulse firearm

ABSTRACT

A gun including a receiver, a barrel assembly slidingly mounted in said receiver, a chamber in a barrel of said barrel assembly for receiving a cartridge with a base for discharge, a bolt slidingly mounted in said receiver for longitudinal displacement respective to said receiver and said barrel assembly and arranged to receive a rearward impulse by said cartridge when discharged, cooperating means in said cartridge and barrel assembly for imparting thereto a forward impulse equal to the rearward impulses received by said bolt through said base, and mechanical means for applying the impulses in said bolt and barrel assembly each against the other while under the urgings of such impulses to produce a zero velocity respective to each other and to said receiver, said mechanical means including a forward face on said barrel assembly, a stop plate and means for mounting said stop plate to said bolt so as to contact said forward face for stopping relative displacement between said bolt and barrel assembly responsive to discharge of the cartridge when said bolt is displaced to an open position relative to said barrel assembly.

United States Patent Findlay et al.

54 EQUAL IMPULSE FIREARM [72] Inventors: David Findlay; Arnold L. Fowler, both of Guilford, Conn.

[73] Assignee: The United States 01 America as represented by the Secretary of the Army 22 Filed: Feb. 23, 1965 211 Appl.No.: 435,410

[56] References Cited UNITED STATES PATENTS 891,778 6/1908 Martens ..89/l59 2,567,826 9/1951 Prache ..89/l4.3

Primary Examiner-Samuel W. Engle Attorney-Harry M. Saragovitz, Edward J. Kelly, Herbert Berl and Albert E. Arnold, Jr.

[451 June 27, 1972 EXEMPLARY CLAIM A gun including a receiver, a barrel assembly slidingly mounted in said receiver, a chamber in a barrel of said barrel assembly for receiving a cartridge with a base for discharge, a bolt slidingly mounted in said receiver for longitudinal displacement respective to said receiver and said barrel assembly and arranged to receive a rearward impulse by said cartridge when discharged, cooperating means in said cartridge and barrel assembly for imparting thereto a forward impulse equal to the rearward impulses received by said bolt through said base, and mechanical means for applying the impulses in said bolt and barrel assembly each against the other while under the urgings of such impulses to produce a zero velocity respective to each other and to said receiver, said mechanical means including a forward face on said barrel assembly, a stop plate and means for mounting said stop plate to said bolt so as to contact said forward face for stopping relative displacement between said bolt and barrel assembly responsive to discharge of the cartridge when said bolt is displaced to an open position relative to said barrel assembly.

4 Claims, 5 Drawing Figures EQUAL IMPULSE FIREARM This invention relates to firearms and pertains more particularly to those firearms which are of recoilless type.

One of the most troublesome problems encountered in automatic gun firing is the reactionary or recoil force which is produced in the gun by discharge of a cartridge therein because, due to this recoil force, muzzle climb and other undesirable conditions are produced which affect the effectiveness of the gun.

Consequently, guns have to be designed to control or minimize the recoil forces as much as possible. Most of the designs make use of a controlled jet action of the discharge gases to oppose the rearward impulses but none has proven to be entirely satisfactory.

It is, therefore, the principle object of this invention to provide a gun in which the recoil forces produced from the discharge of a cartridge therein are divided to produce two equal impulses which are applied mechanically each against the other to produce a zero velocity respective to each other so that none of the recoil forces is transferred to the gun receiver.

It is the more specific object of this invention to provide in a gun a bolt assembly and a barrel assembly which are displaced relative to each other and to the gun receiver with means for imparting equal impulses in opposite directions to the bolt and barrel assemblies from the discharge forces and means for mechanically applying the impulses each against the other to produce zero velocities in the bolt and barrel assemblies relative to each other and to the receiver.

The specific nature of the invention as well as other objects and advantages thereof will clearly appear from a description of a preferred embodiment as shown in the accompanying drawings in which:

FIG. 1 is a schematic top view of a firearm with the bolt assembly'shown in the closed battery position relative to the barrel;

FIG. 2 is a view similar to FIG. 1 but showing the chambcred cartridge discharged and the bolt and barrel assemblies displaced thereby to the relative open loading position;

FIG. 3 is a view similar to FIGS. 1 and 2 but showing the bolt and barrel assemblies in impact at the termination of their relative open displacement;

FIG. 4 is a pressure-time curve produced by discharge of the cartridge in the gun; and

FIG. 5 is an enlarged fragmentary view of the breech end of the barrel and the bolt in longitudinal cross-section.

Shown in the figures is a gun 12 which includes a receiver 14, a barrel assembly 16 and a bolt assembly I8. Barrel assembly 16 includes a barrel 20 on the front end of which there is provided a muzzle brake 22 for converting discharge gases flowing through barrel bore 23 to a forward impulse in the barrel. Mounted in the rear end of barrel 20 is a barrel extension 24 with an integral bearing portion 26 which has sliding contact with the inside of receiver 14. Barrel assembly 16 is further supported for sliding displacement by a bearing surface 28 which slidingly engages the exterior surface of barrel 20 at the front end of receiver 14.

Barrel extension 24 is provided with a forwardly facing surface 30 at the front end and is chambered at 32 to receive a cartridge 34. Cartridge 34 includes a case 36 of bottleneck configuration with a forwardly facing shoulder 38 and chamber 32 has a section 40 which mates therewith.

Bolt assembly 18 includes a bolt 50 which is mounted for sliding longitudinal displacement in receiver 14 for performing the normal functions of ramming cartridge 34 into chamber 32, supporting the base thereof at discharge and extracting the fired case 36. A pair of rods 52 are mounted in bolt 50 so as to extend forwardly therefrom through clearance holes 54 in bearing portion 26 and the front ends are fixed in a stop plate 56 slidable in receiver 14 so that bolt assembly 18 and barrel assembly 16 are longitudinally displaceable relative to each other in the receiver. Rods 52 are long enough to permit sufficient relative displacement of barrel assembly 16 and bolt assembly 18 for the normal functions thereof. Mounted on each of the rods 52 between stop plate 56 and bearing portion 26 is a compressible coil spring 58 for biasing bolt assembly 18 and barrel assembly 16 together from an open loading position to a closed battery position relative to each other. The group consisting of barrel assembly 16 and bolt assembly 18 is located in receiver 14 at a firing position intermediate the forward and rearward limits of free displacement in the receiver by soft positioning springs represented at 60.

When cartridge 34 is discharged, a rearward impulse is imparted to bolt assembly 18 by the base of the cartridge, noted at 62, and a forward impulse is imparted to barrel assembly 16 by shoulder 38. Because the inside area 64 of shoulder 38 is necessarily smaller than the inside area 66 of base 62, the forward impulse imparted to bolt assembly 16 has to be augmented to equal the rearward impulse imparted to the bolt assembly. Therefore, when the projectile of cartridge 34 exits from barrel 20, prior to impact between stop plate 56 and face 30 of barrel extension 24, a portion of the discharge gases are bled through muzzle brake 22 to provide the additional impulse. Thus, when stop plate 56 and face 30 do impact, the velocity of bolt assembly 18 and barrel assembly 16 are zero relative to each other and to receiver 14 and where the barrel assembly and the bolt assembly are symmetrical in design and operation, little or no discharge force is transmitted to the receiver to affect the aim of the gun even if fired at a high cyclic rate. The proper correlationships inside area 66 of base 62, inside area 64 of shoulder 38, bolt assembly 18, barrel assembly l6, and muzzle brake 22 are easily determined from the following analysis:

I Impulse received by bolt assembly 18 from the base area of cartridge case 36.

I Impulse received by barrel assembly 16 from the inside shoulder area 66 of cartridge case 36.

I, Impulse received by the barrel assembly from muzzle brake 22.

Equation I I I, I

but I,,=A I Pdt where A, inside area 66 of cartridge case 36 and I Pdt area under the pressure-time curve (See FIG.

and l,= (A A,,) I Pdt where A, area of bore 23 If we take the velocity of both barrel assembly 16 and bolt assembly 18 as zero prior to firing of cartridge 34 (FIG. 1), and examine the situation after projectile exit (FIG. 3) when the bolt and barrel assemblies impact, we find MR n a n im Equation II M mass of bolt assembly 18 M mass of barrel assembly 16 V velocity of the bolt assembly V velocity of the barrel assembly Equation 11 shows that at the impact between bolt assembly 18 and barrel assembly 16 all momentum thereof with respect to each other and to receiver 14 comes to a halt (FIG. 3), and without any impacts or other forces (except the small forces of the positioning springs 60) on receiver 14 where the designs and operations of the barrel assembly and the bolt assembly are symmetrical.

Although a particular embodiment of the invention has been described in detail herein, it is evident that many variations may be devised within the spirit and scope thereof and the following claims are intended to include such variations.

We claim:

1. A gun including a receiver, a barrel assembly slidingly mounted in said receiver, a chamber in a barrel of said barrel assembly for receiving a cartridge with a base for discharge, a bolt slidingly mounted in said receiver for longitudinal displacement respective to said receiver and said barrel assembly and arranged to receive a rearward impulse by said cartridge when discharged, cooperating means in said cartridge and barrel assembly for imparting thereto a forward impulse equal to the rearward impulses received by said bolt through said base, and mechanical means for applying the impulses in said bolt and barrel assembly each against the other while under the urgings of such impulses to produce a zero velocity respective to each other and to said receiver, said mechanical means including a forward face on said barrel assembly, a stop plate and means for mounting said stop plate to said bolt so as to contact said forward face for stopping relative displacement between said bolt and barrel assembly responsive to discharge of the cartridge when said bolt is displaced to an open position relative to said barrel assembly.

2. The gun as defined in claim 1 wherein said barrel assembly includes a barrel extension and said barrel includes a bearing surface each having contact with said receiver for slidingly supporting said barrel assembly and wherein said means for mounting said stop plate to said bolt include a pair of rods extending through clearance holes in said barrel extension and respectively mounted at one end to said bolt and at the opposite end to said stop plate to fix said stop plate to said bolt.

3. The gun as defined in claim 2 and including a compressible coil spring mounted on each of said rods between said stop plate and said barrel extension for biasing said bolt to a closed position respective to said barrel assembly.

4. The gun as defined in claim 2 and including a group including said barrel assembly and said bolt mounted in said receiver for limited free longitudinal displacement therein, and soft cushioning springs disposed between said receiver and said bolt and between said receiver and said stop plate for resiliently positioning said group at a firing position intermediate the limits of free displacement thereof. 

1. A gun including a receiver, a barrel assembly slidingly mounted in said receiver, a chamber in a barrel of said barrel assembly for receiving a cartridge with a base for discharge, a bolt slidingly mounted in said receiver for longitudinal displacement respective to said receiver and said barrel assembly and arranged to receive a rearward impulse by said cartridge when discharged, cooperating means in said cartridge and barrel assembly for imparting thereto a forward impulse equal to the rearward impulses received by said bolt through said base, and mechanical means for applying the impulses in said bolt and barrel assembly each against the other while under the urgings of such impulses to produce a zero velocity respective to each other and to said receiver, said mechanical means including a forward face on said barrel assembly, a stop plate and means for mounting said stop plate to said bolt so as to contact said forward face for stopping relative displacement between said bolt and barrel assembly responsive to discharge of the cartridge when said bolt is displaced to an open position relative to said barrel assembly.
 2. The gun as defined in claim 1 wherein said barrel assembly includes a barrel extension and said barrel includes a bearing surface each having contact with said receiver for slidingly supporting said barrel assembly and wherein said means for mounting said stop plate to said bolt include a pair of rods extending through clearance holes in said barrel extension and respectively mounted at one end to said bolt and at the opposite end to said stop plate to fix said stop plate to said bolt.
 3. The gun as defined in claim 2 and including a compressible coil spring mounted on each of said rods between said stop plate and said barrel extension for biasing said bolt to a closed position respective to said barrel assembly.
 4. The gun as defined in claim 2 and including a group including said barrel assembly and said bolt mounted in said receiver for limited free longitudinal displacement therein, and soft cushioning springs disposed between said receiver and said bolt and between said receiver and said stop plate for resiliently positioning said group at a firing position intermediate the limits of free displacement thereof. 